This proposal describes a five year longitudinal study of the nature and quality of effective marital functioning in old and middle-aged couples. The focus of the research is on normal aging and on long-term first marriages. Marriage is viewed as a singularly important interpersonal relationship that plays an increasingly important role in the maintenance of well-being in old age. Our previous work with young married couples has shown that current and future levels of marital satisfaction can be best understood by directly observing the couple as they interact, especially when they are attempting to resolve problem areas in their marriage. We propose to study 140 married couples who differ as to age (old versus middle-age) and marital satisfaction (satisfied versus dissatisfied) and to observe three different kinds of marital interactions in the laboratory on two different occasions two years apart. During each interaction a multi- method data collection will be carried out that includes fine- grained measurement from a number of different domains. Longitudinal change in marital satisfaction and health will be assessed as well. The research addressed five specific aims: (a) to study the nature of marital interaction in old age; (b) to determine how happy and unhappy marriages differ in old-age and in middle age; (c) to find predictors of change in relationship satisfaction over a two year period in old-age and in middle age; (d) to determine the stability of marital interaction over a two year period in old-age and in middle age; and (e) to study the relations among marital satisfaction, marital interaction, and health in old-age and in middle age.